xtremerevolution Posted January 25, 2010 Author Report Share Posted January 25, 2010 that's roughly 57.4mm at the throat... so about 375cfm... here's what i came up with... According to that, I should have gotten a decent power increase, especially with an opened up exhaust and a CAI. i see a peak increase of 4HP... and 3 lbs of torque.... from the rockers alone anyway. adding in the exhaust and CAI? i'd have to be much more familiar with 3800 stuff to know for sure. What do you suppose is holding up my performance? Should I look into polishing the throttle body and porting out parts of it that can be without altering the MAF tables? The LIM is also ported. 4hp is a pretty terrible way to spend $300 if that is indeed all I gained. Basically, where do you think my biggest restriction is? Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted January 25, 2010 Report Share Posted January 25, 2010 heads. without a doubt, heads are the biggest restiction to any 3800... i'm gonna try and quote john lingenfelter(EDIT: found exact quote): "The worlds's best cam combined with a poor set of heads will produce an engine that's a dog. But bolt on a set of great heads even with a poor cam and that engine will still make great power." essentially, if the engine can't breath, nothing you do will help it. how many powerful n/a 3800 motors do you know of? and how badly did they have to open up the heads to get there? are there any aftermarket castings? this is why people will happily boost a 3800 to reach a certain power goal... it's just too damn hard to do it without a blower... Quote Link to comment Share on other sites More sharing options...
xtremerevolution Posted January 25, 2010 Author Report Share Posted January 25, 2010 heads. without a doubt, heads are the biggest restiction to any 3800... i'm gonna try and quote john lingenfelter(EDIT: found exact quote): "The worlds's best cam combined with a poor set of heads will produce an engine that's a dog. But bolt on a set of great heads even with a poor cam and that engine will still make great power." essentially, if the engine can't breath, nothing you do will help it. how many powerful n/a 3800 motors do you know of? and how badly did they have to open up the heads to get there? are there any aftermarket castings? this is why people will happily boost a 3800 to reach a certain power goal... it's just too damn hard to do it without a blower... Is this in regard to the size of the ports for the heads, the size of the valves, or the design of the ports? I can definitely go insane with a porting job on a set of heads, but I'm not going to start if I'm not 100% sure that it will produce any gains. Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted January 25, 2010 Report Share Posted January 25, 2010 Is this in regard to the size of the ports for the heads, the size of the valves, or the design of the ports? EVERYTHING. larger valves can help flow more, but only if the port can flow it. and with heads, and most any other part of an engine, it's all a compromise: smaller ports/valves are great for low-end torque, but suffer up top due to not being able to flow enough. larger ports/valves are great for higher RPM torque(and HP since HP is only a calculation based on RPM and torque), but suffer in the low-RPM ranges due to a larger port flowing the same amount of air as a smaller one will have less velocity... design of ports: kind of stuck with how the heads were cast. you can only do so much before running into a water jacket or other obstruction... Quote Link to comment Share on other sites More sharing options...
xtremerevolution Posted January 25, 2010 Author Report Share Posted January 25, 2010 Is this in regard to the size of the ports for the heads, the size of the valves, or the design of the ports? EVERYTHING. larger valves can help flow more, but only if the port can flow it. and with heads, and most any other part of an engine, it's all a compromise: smaller ports/valves are great for low-end torque, but suffer up top due to not being able to flow enough. larger ports/valves are great for higher RPM torque(and HP since HP is only a calculation based on RPM and torque), but suffer in the low-RPM ranges due to a larger port flowing the same amount of air as a smaller one will have less velocity... design of ports: kind of stuck with how the heads were cast. you can only do so much before running into a water jacket or other obstruction... That's mostly what I was thinking. I'm just wondering how much of a difference porting will actually make, and I don't know too many people who have gone off porting L27 heads. Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted January 25, 2010 Report Share Posted January 25, 2010 if i had an engine apart, at the absolute minimum, i would be removing the casting flash and gasket matching everything... that alone will do enough to make noticeable difference. beyond that, a flowbench would be VERY beneficial... Quote Link to comment Share on other sites More sharing options...
xtremerevolution Posted January 25, 2010 Author Report Share Posted January 25, 2010 if i had an engine apart, at the absolute minimum, i would be removing the casting flash and gasket matching everything... that alone will do enough to make noticeable difference. beyond that, a flowbench would be VERY beneficial... I wish I had access to a flow bench, but I don't. I'd be doing it all by hand and crossing my fingers for the most part. I would think my port work on the Jag V12 heads was pretty damn good though. Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted January 25, 2010 Report Share Posted January 25, 2010 I wish I had access to a flow bench, but I don't. I'd be doing it all by hand and crossing my fingers for the most part. I would think my port work on the Jag V12 heads was pretty damn good though. ya never know... a ghetto setup for a flow bench that i've considered involves a shop vac and a vacuum guage... varying amount of vacuum between ports mean they flow differently... or at least that's the theory of it. Quote Link to comment Share on other sites More sharing options...
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